1. Field of the Invention
The present invention relates to a semiconductor memory device, and more particularly, to a non-volatile semiconductor memory device such a flash type EEPROM (Electrically Erasable Programmable Read Only Memory, and hereafter called a flash memory), and the like. In this flash memory, stored information (data) is electrically and collectively erasable, and then the stored information can be rewritten.
2. Description of the Related Art
Recently, in accordance with popularization of computers, word processors, and the like, a plurality of semiconductor memory devices, typically non-volatile semiconductor memory devices, e.g., flash memory, used in such information processors, have been developed and produced.
The flash memory, which is one kind of non-volatile semiconductor memory device, can be made programmable by the user. Further, the flash memory can be rewritten by electrically and collectively erasing the stored data, and then by programming. In recent years, a flash memory having a boot block (boot block type flash memory) has been also developed. In this boot block type flash memory, a special memory area (boot block), which can only be rewritten in a special manner, is provided. Note, in the boot block, for example, a BIOS (Basic Input Output System), 0S (operating system), and the like, can be stored.
Nevertheless, in the boot block type flash memory, a memory area corresponding to the boot block is constituted by hardware, and thus when providing a normal type flash memory not having a boot block and having a storage capacity corresponding to the total storage capacity of the boot block type flash memory, a different chip must be designed. Therefore, when providing both boot block type flash memory and normal type flash memory, development efficiency for the two types of flash memory becomes low, and thus the cost thereof cannot be decreased.
Further, when providing the boot block type flash memory as a normal type flash memory not having a boot block, a storage capacity of the normal type flash memory is specified as a storage capacity excluding the boot block in the boot block type flash memory. Namely, when using the boot block type flash memory as a normal type flash memory, the boot block cannot be used, and the storage capacity thereof becomes small.